Traveling hydraulic working machine

Abstract

A modification torque ΔT and a torque converter speed ratio e is computed from input and output revolution speeds of a torque converter 31. A first determination coefficient α corresponding to the speed ratio e, and a second determination coefficient β corresponding to a pump pressure are computed. A selector 87 selects the smaller one of these coefficients as a determination coefficient γ, and the modification torque ΔT is multiplied by γ to provide a modification torque ΔTA. An adder 89 adds the modification torque ΔTA (negative value) to a pump base torque TR to provide a modified pump base torque TRA, whereby a maximum pump absorption torque TRA is controlled so as to become TRA. The maximum pump torque reducing control can then be performed while accurately confirming a work situation during the combined operation of travel and a working actuator.

Description

TECHNICAL FIELD[0001]The present invention relates to a traveling hydraulic working machine, such as a wheel loader or a telescopic handler, in which a transmission is driven by a prime mover (engine) to travel the machine and a hydraulic pump is also driven by the prime mover to operate a working actuator, thereby carrying out predetermined work.BACKGROUND ART[0002]In a known general traveling hydraulic working machine, a hydraulic pump is of the fixed displacement type, and the maximum absorption torque of the pump is also constant (fixed). Therefore, a proportion at which the engine output torque is distributed between respective operations of the hydraulic pump and travel (transmission) is constant and so is a maximum torque for the travel.[0003]In connection with such a known general traveling hydraulic working machine, Japanese Patent No. 2968558 proposes an improved one employing a variable displacement hydraulic pump in such a manner that the maximum absorption torque of the...

AI Technical Summary

Benefits of technology

"The present invention provides a traveling hydraulic working machine that can perform the maximum pump torque reducing control while accurately confirming a work situation during the combined operation of travel and a working actuator. The machine comprises first detecting means for detecting whether the sum of absorption torque of the hydraulic pump and travel torque exceeds the output torque of the prime mover, second detecting means for detecting the operating situation of the traveling means, and pump torque modifying means for modifying maximum absorption torque of the hydraulic pump depending on the operating situation of the traveling means. This allows for a satisfactory combination of work and improved workability and efficiency."

Problems solved by technology

Accordingly, a satisfactory result is obtained in limited types of work, whereas the workability deteriorates and the working efficiency decreases in some type of work.

Also, assuming the case that the front load is increased in a state where, for example, snow removing work is carried out at a constant speed while lowering a boom, if the maximum pump torque reducing control is performed, a larger travel force is produced and the snow removing work cannot be carried out at the constant speed.

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